EP0373677A2 - Lentille pour un système de balayage optique - Google Patents

Lentille pour un système de balayage optique Download PDF

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Publication number
EP0373677A2
EP0373677A2 EP89123297A EP89123297A EP0373677A2 EP 0373677 A2 EP0373677 A2 EP 0373677A2 EP 89123297 A EP89123297 A EP 89123297A EP 89123297 A EP89123297 A EP 89123297A EP 0373677 A2 EP0373677 A2 EP 0373677A2
Authority
EP
European Patent Office
Prior art keywords
lens
lens system
entrance pupil
positive power
focal length
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP89123297A
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German (de)
English (en)
Other versions
EP0373677B1 (fr
EP0373677A3 (fr
Inventor
Hiroyuki Dainippon Screen Mfg. Co. Ltd. Shirota
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Dainippon Screen Manufacturing Co Ltd
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Dainippon Screen Manufacturing Co Ltd
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Publication date
Application filed by Dainippon Screen Manufacturing Co Ltd filed Critical Dainippon Screen Manufacturing Co Ltd
Publication of EP0373677A2 publication Critical patent/EP0373677A2/fr
Publication of EP0373677A3 publication Critical patent/EP0373677A3/fr
Application granted granted Critical
Publication of EP0373677B1 publication Critical patent/EP0373677B1/fr
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Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B13/00—Optical objectives specially designed for the purposes specified below
    • G02B13/22—Telecentric objectives or lens systems
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B13/00—Optical objectives specially designed for the purposes specified below
    • G02B13/0005—Optical objectives specially designed for the purposes specified below having F-Theta characteristic
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
    • G02B26/08—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light
    • G02B26/10—Scanning systems
    • G02B26/12—Scanning systems using multifaceted mirrors
    • G02B26/123—Multibeam scanners, e.g. using multiple light sources or beam splitters
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B9/00—Optical objectives characterised both by the number of the components and their arrangements according to their sign, i.e. + or -
    • G02B9/60—Optical objectives characterised both by the number of the components and their arrangements according to their sign, i.e. + or - having five components only

Definitions

  • the present invention relates to a lens system, and more particularly, to a lens system which is applied to an optical beam scanner, such as a laser printer, which scans a plurality of optical beams on a recording surface.
  • an optical beam scanner such as a laser printer
  • the lens system has a telecentric characteristic that all principal rays substantially vertically enter the recording surface RS, so that an image size in a main scanning direction does not vary even if the recording surface RS is displaced in the direction of the optical axis Z, for example as is well known in the art.
  • the f-sin ⁇ lens system shown in Fig. 5 has no telecentric characteristic, so that an image size in a main scanning direction varies with the displacement of the recording surface RS in the direction of the optical axis Z of the f-sin ⁇ lens system. Therefore, the lens system can't be employed in the optical beam scanner such as a laser printer requiring that the image can be recorded on the recording surface RS in high accuracy.
  • the above lens system satisfies following: 0.6 ⁇ (r2/r3) ⁇ 2.1 -0.43 ⁇ (f2/f) ⁇ -0.21 1.3 ⁇ (f5/f) ⁇ 2.6
  • r2 is a radius of curvature of a surface of the first lens, which is directed to the recording surface
  • r3 is a radius of curvature of a surface of the second lens, which is directed to the entrance pupil
  • f2 is a focal length of the second lens
  • f5 is a focal length of the fifth lens.
  • f is a focal length of the lens system.
  • the present invention is directed to an optical beam scanner for scanning a plurality of optical beams on a recording surface.
  • the optical beam scanner comprises: a light source for generating the plurality of optical beams; a deflector for deflecting the optical beams outgoing from the light source; and a lens system for imaging the optical beams deflected by the deflector on the recording surface.
  • the lens system comprises: (a) a first lens group having an entrance pupil, which includes (a-1) a first lens in the form of meniscus having a positive power and having a concave surface which is directed to the entrance pupil, (a-2) a second lens having a negative power, (a-3) a third lens in the form of meniscus having a positive power, and a fourth lens having positive power; and (b) a second lens group including a fifth lens having a positive power. Further, the first through fifth lenses are successively disposed in order from the entrance pupil side.
  • a principal object of the present invention is to provide a lens system which has a telecentric property and an excellent f-sin ⁇ characteristic.
  • Another object of the present invention is to provide an optical beam scanner which can scan the plurality of optical beams on the recording surface in high accuracy while improving a quality of an image formed on the recording surface.
  • Fig. 6 illustrates a preferred embodiment of a lens system according to the present invention.
  • the lens system is formed with a rear lens group R L and a front lens group F L , which are arranged in order from a recording surface RS side at a prescribed interval.
  • the front lens group F L is formed with first, third and fourth meniscus lenses L1, L3 and L4 having positive power and a second lens L2 having negative power, as shown in Fig. 6.
  • the first to fourth lenses L1 to L4 are arranged in order from an entrance pupil EP side at prescribed intervals, while all of concave surfaces S1, S3 S5 and S7 of the first to fourth lenses L1 to L4 are directed toward the entrance pupil EP.
  • the rear lens group R L is formed with a fifth lens L5 having positive power, and a convex surface S10 of the fifth lens L5 is directed toward the recording surface RS.
  • the lens system having the aforementioned structure satisfies: 0.6 ⁇ (r2/r3) ⁇ 2.1 (1) -0.43 ⁇ (f2/f) ⁇ -0.21 (2) 1.3 ⁇ (f5/f) ⁇ 2.6 (3)
  • r2 is a radius of curvature of a surface S2 of the first lens L1, which is directed toward the recording surface RS
  • r3 is a radius of curvature of the surface S3 of the second lens L2
  • f2 is a focal length of the second lens L2
  • f5 is a focal length of the fifth lens L5
  • f is a focal length of the lens system.
  • the inequality (1) shows the condition for correcting the spherical aberration, astigmatism and curvature of image surface. That is, when the value (r2/r3) is not more that 0.6, both of the meridional and sagittal image surfaces are inclined toward the negative (-) side while correction of the spherical aberration is insufficient. When value (r2/r3) is more than 2.1, the spherical aberration is excessively corrected while the meridional image surface is inclined toward the positive (+) side, whereby astigmatism at an end of a field angle is increased. Further, the f-sin ⁇ characteristic is degraded also.
  • the inequality (2) shows the condition for the curvature of image surface. That is, when the value (f2/f) is not more than -0.43 the curvature of the sagittal image surface is increased. When the value (f2/f) is not less than -0.21, both of the meridional and sagittal image surfaces are inclined toward the negative (-) side.
  • the inequality (3) shows the condition for the curvature of image surface and the condition that the lens system has a telecentric property. That is, when the value (f5/f) is not more that 1.3, the meridional image surface is inclined toward the negative (-) side while the telecentric characteristic is degraded. On the other hand, when the value (f5/f) is more than 2.6, the sagittal image surface is inclined in spite of improving the telecentric characteristic of the lens system.
  • the lens system which has both of telecentric and f-sin ⁇ characteristics can be obtained, which further has the following characteristics;
  • Table 1 shows lens data of a first example according to a lens system structured along Fig. 6.
  • Table 1 r i d i n i i 1 -23.26 1.72 1.77861 2 -20.56 7.61 3 -17.10 5.00 1.61655 4 -186.05 1.90 5 -105.55 7.92 1.77861 6 -35.28 0.12 7 -106.55 6.00 1.77861 8 -41.31 122.10 9 ⁇ 13.59 1.51462 10 -98.17
  • ⁇ represents a wavelength of a laser beam
  • d O represents a space between the entrance pupil EP and the concave surface S1 of the first lens L1.
  • the focal length f2, f5 of the second and fifth lens L2, L5 is -30.9, 190.8, respectively, although this is not shown in Tables 1 and 2.
  • Figs. 7A, 7B and 7C illustrate spherical aberration, astigmatism and f-sin ⁇ characteristic of the lens system having the aforementioned structure, respectively.
  • Table 3 shows lens data of a second example according to the lens system.
  • Table 3 r i d i n i i 1 -10.50 1.05 1.77861 2 -10.85 14.59 3 -17.90 1.00 1.61655 4 -201.87 1.27 5 -60.73 3.31 1.77861 6 -30.68 0.10 7 -456.16 5.50 1.77861 8 -35.92 106.99 9 ⁇ 12.68 1.51462 10 -104.67
  • the focal length f , the F-number F NO etc. of the lens system having the aforementioned lens data are set as shown in Table 4.
  • the focal length f2, f5 of the second and fifth lens L2, L5 is -31.9, 203.4, respectively, although this is now shown in Tables 3 and 4.
  • the focal length f , the F-number F NO etc. of the lens system having the aforementioned lens data are set as shown in Table 8.
  • Table 8 f F NO ⁇ d0 100.00 20.00 632.8 nm 10.00
  • Figs 11A, 11b and 11C illustrate spherical aberration, astigmatism and f-sin ⁇ characteristic of the lens system having the aforementioned structure, respectively.
  • Table 11 shows lens data of a sixth example according to the lens system.
  • Table 11 r1 d i n i i 1 -19.75 3.40 1.77861 2 -20.13 13.96 3 -25.84 5.00 1.61655 4 550.00 1.18 5 -132.88 2.84 1.77861 6 -50.21 0.10 7 -190.57 3.50 1.77861 8 -51.97 46.55 9 ⁇ 11.26 1.51462 10 -68.45
  • the focal length f2, f5 of the second and fifth lens L2, L5 is -39.9, 133.0, respectively, although this is not shown in Tables 11 and 12.
  • the focal length f , the F-number F NO etc. of the lens system having the aforementioned lens data are set as shown in Table 14.
  • the focal length f2, f5 of the second and fifth lens L2, L5 is -26.7, 260.0, respectively, although this is not shown in Tables 13 and 14.
  • Figs 13A, 13B and 13C illustrate spherical aberration, astigmatism and f-sin ⁇ characteristic of the lens system having the aforementioned structure, respectively.
  • the spherical aberration of the lens system is extremely small as understood from the spherical aberration diagrams (Figs. 7A, 8A, 9A, 10A, 11A, 12A, and 13A), and the astigmatism thereof is also extremely small as understood from the astigmatism diagrams (Figs. 7B, 8B, 9B, 10B, 11B, 12B, and 13B). Further, the lens system structured as above has an excellent f-sin ⁇ characteristic, as understood from the f-sin ⁇ characteristic diagrams (Figs. 7C, 8C, 9C, 10C, 11C, 12c and 13C).
  • Fig. 14 is a perspective view showing an optical system of an optical beam scanner, which scans a plurality of laser beams on a recording surface, to which the aforementioned lens system can be applied.
  • a laser beam B1 outgoing from a laser tube 11 is projected onto a non-polarizing beam splitter 12, to be divided into a scanning beam B2 and a reference beam B3.
  • the scanning beam B2 reflected by the beam splitter 12 enters an optical modulator system 13 for dividing the scanning beam B2 into a plurality of laser beams and individually modulating the plurality of laser beams in response to image signals being inputted into the optical modulator system 13.
  • the optical modulator system 13 includes a non-polarizing beam splitter 14 and two polarizing beam splitters 15, 16 so as to divide the scanning beam B2 into four laser beams B21, B22, B23, B24.
  • the scanning beam B2 is divided into two laser beams by the beam splitter 14, and then the two laser beams are directed to the beam splitter 15, 16, respectively.
  • the lens system 29 is structured as shown in Fig. 6 and satisfies the above inequation (1) to (3), so as to have a telecentric characteristic. Therefore, the image is recorded on the photosensitive material in high accuracy. Further, the lens system has also an excellent f-sin ⁇ characteristic. Thus, each of scanning locus of the respective laser beams forming the multibeam B5 is made straight. Consequently, the image can be recorded on the photosensitive material not only in high accuracy but also in high quality.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Lenses (AREA)
  • Mechanical Optical Scanning Systems (AREA)
EP89123297A 1988-12-16 1989-12-15 Lentille pour un système de balayage optique Expired - Lifetime EP0373677B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP63319124A JPH07113706B2 (ja) 1988-12-16 1988-12-16 光ビーム走査用レンズ
JP319124/88 1988-12-16

Publications (3)

Publication Number Publication Date
EP0373677A2 true EP0373677A2 (fr) 1990-06-20
EP0373677A3 EP0373677A3 (fr) 1991-05-29
EP0373677B1 EP0373677B1 (fr) 1994-05-04

Family

ID=18106731

Family Applications (1)

Application Number Title Priority Date Filing Date
EP89123297A Expired - Lifetime EP0373677B1 (fr) 1988-12-16 1989-12-15 Lentille pour un système de balayage optique

Country Status (4)

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US (1) US5018807A (fr)
EP (1) EP0373677B1 (fr)
JP (1) JPH07113706B2 (fr)
DE (1) DE68915131T2 (fr)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0506338A1 (fr) * 1991-03-28 1992-09-30 Minnesota Mining And Manufacturing Company Système de lentilles télécentrique à balayage avec correction de la couleur
US5200861A (en) * 1991-09-27 1993-04-06 U.S. Precision Lens Incorporated Lens systems
EP0661573A1 (fr) * 1993-12-29 1995-07-05 Xerox Corporation Système de balayage optique par faisceau multiple ayant rayons de sortie pricipals télécentriques
US5625495A (en) * 1994-12-07 1997-04-29 U.S. Precision Lens Inc. Telecentric lens systems for forming an image of an object composed of pixels
EP1063048A2 (fr) * 1999-06-23 2000-12-27 Sumitomo Electric Industries, Ltd. Appareil de perçage de trous au laser
WO2016116956A1 (fr) * 2015-01-20 2016-07-28 3I - Impresa Ingegneria Italia S.R.L. Équipement d'acquisition d'image pourvu d'un objectif optique télécentrique comportant une lentille cylindrique principale

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3339934B2 (ja) * 1993-09-29 2002-10-28 富士写真光機株式会社 ｆ・θレンズ
US6731320B1 (en) * 1999-03-19 2004-05-04 Applied Materials, Inc. Laser pattern generator
US7164434B2 (en) * 2002-10-11 2007-01-16 Eastman Kodak Company LCD based imaging apparatus for printing multiple formats
US7483196B2 (en) * 2003-09-23 2009-01-27 Applied Materials, Inc. Apparatus for multiple beam deflection and intensity stabilization
JP5249338B2 (ja) * 2008-09-26 2013-07-31 プリズム インク 走査光学装置
JP6521555B1 (ja) * 2019-01-29 2019-05-29 エーエーシーアコースティックテクノロジーズ（シンセン）カンパニーリミテッドＡＡＣ Ａｃｏｕｓｔｉｃ Ｔｅｃｈｎｏｌｏｇｉｅｓ（Ｓｈｅｎｚｈｅｎ）Ｃｏ．，Ｌｔｄ 撮像レンズ

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4269478A (en) * 1978-10-16 1981-05-26 Olympus Optical Co., Ltd. Constant-speed scanning lens system
DE3151221A1 (de) * 1980-12-24 1982-07-22 Canon K.K., Tokyo "abtastobjektiv fuer abtastung mit gleichmaessiger geschwindigkeit mit hohem aufloesungsvermoegen"
JPS59195211A (ja) * 1983-04-19 1984-11-06 Asahi Optical Co Ltd テレセントリツクな４枚構成のｆ−θレンズ系
US4755030A (en) * 1985-11-08 1988-07-05 Matsushita Electric Industrial Co., Ltd. Lens for facsimile or laser printer
EP0288970A2 (fr) * 1987-04-27 1988-11-02 Dainippon Screen Mfg. Co., Ltd. Système optique pour un système d'analyse à spot mobile
EP0360233A2 (fr) * 1988-09-20 1990-03-28 Dainippon Screen Mfg. Co., Ltd. Système de lentilles f-theta télécentrique

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0812324B2 (ja) * 1986-06-20 1996-02-07 株式会社ニコン テレセントリツクｆθレンズ
JPS63253916A (ja) * 1987-04-10 1988-10-20 Hitachi Ltd 光走査装置
JP2584640B2 (ja) * 1987-11-06 1997-02-26 旭光学工業株式会社 レーザービームプリンタ等の走査光学系

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4269478A (en) * 1978-10-16 1981-05-26 Olympus Optical Co., Ltd. Constant-speed scanning lens system
DE3151221A1 (de) * 1980-12-24 1982-07-22 Canon K.K., Tokyo "abtastobjektiv fuer abtastung mit gleichmaessiger geschwindigkeit mit hohem aufloesungsvermoegen"
JPS59195211A (ja) * 1983-04-19 1984-11-06 Asahi Optical Co Ltd テレセントリツクな４枚構成のｆ−θレンズ系
US4755030A (en) * 1985-11-08 1988-07-05 Matsushita Electric Industrial Co., Ltd. Lens for facsimile or laser printer
EP0288970A2 (fr) * 1987-04-27 1988-11-02 Dainippon Screen Mfg. Co., Ltd. Système optique pour un système d'analyse à spot mobile
EP0360233A2 (fr) * 1988-09-20 1990-03-28 Dainippon Screen Mfg. Co., Ltd. Système de lentilles f-theta télécentrique

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN, vol. 9, no. 58 (P-341)[1781], 14th March 1985; & JP-A-59 195 211 (ASAHI KOUGAKU KOGYO K.K.) 06-11-1984 *

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0506338A1 (fr) * 1991-03-28 1992-09-30 Minnesota Mining And Manufacturing Company Système de lentilles télécentrique à balayage avec correction de la couleur
US5200861A (en) * 1991-09-27 1993-04-06 U.S. Precision Lens Incorporated Lens systems
EP0661573A1 (fr) * 1993-12-29 1995-07-05 Xerox Corporation Système de balayage optique par faisceau multiple ayant rayons de sortie pricipals télécentriques
US5512949A (en) * 1993-12-29 1996-04-30 Xerox Corporation Multiple beam raster output scanner optical system having telecentric chief exit rays
US5625495A (en) * 1994-12-07 1997-04-29 U.S. Precision Lens Inc. Telecentric lens systems for forming an image of an object composed of pixels
USRE39424E1 (en) * 1994-12-07 2006-12-12 3M Innovative Properties Company Telecentric lens systems for forming an image of an object composed of pixels
EP1063048A2 (fr) * 1999-06-23 2000-12-27 Sumitomo Electric Industries, Ltd. Appareil de perçage de trous au laser
EP1063048A3 (fr) * 1999-06-23 2003-02-19 Sumitomo Electric Industries, Ltd. Appareil de perçage de trous au laser
WO2016116956A1 (fr) * 2015-01-20 2016-07-28 3I - Impresa Ingegneria Italia S.R.L. Équipement d'acquisition d'image pourvu d'un objectif optique télécentrique comportant une lentille cylindrique principale

Also Published As

Publication number Publication date
US5018807A (en) 1991-05-28
EP0373677B1 (fr) 1994-05-04
EP0373677A3 (fr) 1991-05-29
JPH02163720A (ja) 1990-06-25
DE68915131T2 (de) 1994-12-15
JPH07113706B2 (ja) 1995-12-06
DE68915131D1 (de) 1994-06-09

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